1. Field of the Invention
The present invention relates to a method of a boiler cage floors and more specifically to a method of the construction of boiler cage floors that is preferred for the construction of a large-sized boiler for thermal power plant.
2. Related Art
FIG. 9 is a side view illustrating main constitution of a large-sized boiler for thermal power generator. A boiler frame 2 taking main body of a boiler 1 is the gigantic structure that bearing height reaches 60-100 m. The boiler main body 1 is hung from a sky beam 3 of the boiler frame 2 through a hanging portion 4 to release the thermal expansion downward.
Inside of boiler main body 1, a second and third super-heater 5, a re-heater 6, a primary super-heater 7, an economizer 8 are placed; and the lower parts of the re-heater 6 and the economizer 8 are formed to be an eco-hopper 9. Multiple quantities of wind-boxes 10 are arranged to a furnace wall of the boiler main body 1; and a burner and a fuel pipe arrangement, a combustion air pipe arrangement are connected to the individual wind-box 10. A left area 11 of the boiler frame 2 is the area where coal bunker is placed. The lower area of eco-hopper 9 is assumed a cage part 12, and this cage part 12 is constructed as by floors 13 (13A, 13B, 13C, and 13D) of the plural floor levels.
In construction of the boiler, by building the boiler frame 2 first, while hanging and attaching various components and devices through the hanging portion 4 from the upper portion to the lower portion one after another, the boiler main body is formed.
The re-heater 6, the primary super-heater 7, the economizer 8, and the eco-hopper 9 forming the right side of boiler main body 1 are carried in to the ground of the cage part 12 in a shape of a block or unit for the working efficiency. A lifting device such as a jack or a winch is used, so that each of the blocks/units is lifted to set position and installed. In doing so, when there is any floor 13 in the cage part 12, the floor 13 will block up the route of the block of each components and devices and becomes the obstacle of lifting operation.
Because of this reason, the general method of securing the lifting route of each apparatus block is adopted without attaching any floor 13 within the cage part 12, till the installation of each equipment such as the re-heater 6, the primary superheater 7, the economizer 8, and the eco-hopper 9 is completed. And after the installation of the each equipment was completed, floors 13 (13A, 13B, 13C, and 13D) are built sequentially.
However, when the floors 13 are built by such a general method, the upper portion of the cage part 12 is occupied and closed by the eco-hopper 9. Because of this reason, there are problems that arise the efficiency deteriorates when importing and lifting various components of floors 13 by utilizing the crane since the eco-hopper 9 becomes the obstacle of the lifting operation.
On the other hand, the adoption of a block method of construction for the construction of boiler housing is receiving popular attention in recent years, for reducing both the construction cost and schedule.
An example of the block method of construction is disclosed in the Japanese Patent Number 2,932,818. In this block method of construction columns, girders, braces, middle beams, small beams, floor joists, plunk gratings, a handrail are assembled in a pre-fabrication shop in each predetermined block unit; and the blocks are piled up while they are lifting with a crane in construction field.
According to the block method of construction such as these, the assembling of the block can be performed in the pre-fabrication shop where the good environment condition. Also, there has been a significant reduction of costs and in terms of construction. These elements can be achieved because the assembling of the blocks at the construction site can be taken place at the same time in parallel, by setting the order of production of the block from the low-rise floor to the high-rise floor.
However, if a block method of construction described in the Japanese Patent Number 2,932,818 is applied to construction of the floors 13 after the installation of the completion of the eco-hopper 9 as described above, the eco-hopper 9 will still continue to be an obstacle. As a result, the lifting of huge blocks with the crane becomes more difficult; and the introduction of the block method of construction becomes practically impossible.